A000869 Number of switching networks with C(2,n) acting on domain and GL(3,Z2) acting on range. (Formerly M3620 N1470)

4, 27, 14056, 104751025086, 14737381492157353997140846, 583807825091767184801127161305581049499763751729421166

Offset

1,1

Comments

Next term has 112 digits. - Sean A. Irvine, Jan 24 2012

References

M. A. Harrison, On the number of classes of switching networks, J. Franklin Instit., 276 (1963), 313-327.

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..10

Index entries for sequences related to switching networks

Example

a(n) = (8^(2^n) + 22*2^(2^n + 2^(n-1) + n) - 22*2^(2^n + 2^(n-1)) + 21*4^(2^n) + 56*2^(2^n) + 42*2^(n + 2^n) + 56*2^(2^(n-1) + n) - 56*2^(2^(n-1)) + 48*2^n)/(168*2^n). - Sean A. Irvine, Jan 24 2012

Prog

(Magma) [(8^(2^n)+22*2^(2^n+2^(n-1)+n)-22*2^(2^n+2^(n-1))+21*4^(2^n)+56*2^(2^n)+42*2^(n+2^n)+56*2^(2^(n-1)+n)-56*2^(2^(n-1))+48*2^n)/(168*2^n): n in [1..11]]; // Vincenzo Librandi, Mar 28 2012

Crossrefs

Sequence in context: A132646 A254866 A292968 * A132640 A307031 A306823

Adjacent sequences: A000866 A000867 A000868 * A000870 A000871 A000872

Keyword

nonn,easy

Author

N. J. A. Sloane

Extensions

More terms from Sean A. Irvine, Jan 23 2012

Status

approved